Cooling system for photoprinting mechanisms



J. H. HRUBY Jun 13, 1944.

COOLING SYSTEM FOR PHOTOPRINTING MECHANISMS Filed Sept. 3, 1942 WRW 00 Wm. H H 7 u o d M W7 w ATTORNEYS Patented June 13, 1944 UNITED STATES PATENT OFFICE COOLING SYSTEM FOR PHOTOPRINTING MECHANISMS Joseph H. Hruby, Chicago, Ill., assignor to Charles Bruning' Company, Inc., New York, N. Y., a corporation of New York Application September 3, 1942, Serial No. 457,138 4 Claims. (Cl. 95-775) This invention relates to improvements in vide a cooling system whereby heat can be reprinting machines and relates more particularly moved from the interior of the printing cylinder to an improved cooling system for use in rotary without decreasing the temperature of the lamp' photo-printing mechanisms. obiectionably.

Printing mechanisms of the type referred to 5 Another object of the invention is to provide a above include a glass cylinder within which is cooling system for the interior of a printing mounted a lighting unit so that light may be cylinder which will maintain the temperature projected through a tracing or other material on within the cylinder uniform. the surface of the cylinder and onto a sensitized A further object of the invention is to provide paper which is in close contact with the surface a system whereby the interior of the cylinder of the tracing or other material. The paper and is cooled without deposition of dust and dirt on tracing are maintained in close contact by means the cylinder and whereby the bands in engageof a plurality of belts that pass around the exment with. the cylinder are cooled to prevent terior surface'of the cylinder. The belts are overheating of the sensitized paper.

driven to cause the cylinder to rotate thereby l5 Yet another object of the invention is to propermitting the tracings or other material and vide a cooling system as aforesaid wherein the the sensitized paper to be fed between the belts structure is such that the ends of the cylinder and the cylinder and discharged therefrom. can be effectively sealed, thereby preventing the With the type of lighting elements used in escape of ozone. such printing devices, a considerable amount of 20 A further object of the invention is to provide heat is given off which heats the cylinder and a cooling system of the character above set forth the belts to such an extent that the sensitized wherein a portion of the cooling mechanism paper may be damaged during its passage serves as a light shield for predetermined porthrough the device. tions of the cylinder.

Many different systems for cooling the cyling In accordance with the present invention, I ders have been suggested in the prior art, but have provided a printing machine of the charall of these systems have had certain undesirable acter described above including a cooling system characteristics. For example, it has been sugin the form of a heat exchanging element disgested that air may be directed through the inposed Within the cylinder through which air terior of the cylinder or against the surface of 30 may be blown to absorb air from the interior the cylinder in order to remove heat therefrom. of the cylinder. With this arrangement the ends In those systems utilizing, for example, merof the cylinder may be closed completely so that cury vapor lamps for illuminating the cylinder, dust and dirt cannot enter the cylinder and canthe use of a cooling current of air i objectionnot be deposited on the interior thereof. able for the reason that the cooling air has a 35 In addition, the cooling system may include tendency to reduce the temperature of the lamp. means for directing a current of air between the Inasmuch as such lamps are most efiicient at flights of the belts that engage the cylinder so relatively high operating temperatures, the coolthat a maximum amount of heat may be dissiing of the lamp reduces its efiiciency and if the pated from the belts. p is cooled unequally throughout its length, .For a better understanding of the present inunequal illumination of the cylinder and unequal vention, reference may be had to the accomexposure of the paper on the exterior thereof panying drawing in which the single figure is a may result. perspective view of a typical form of device em- In those systems involving cooling by means bodying the present invention, partly broken of air blasts directed against the exterior of the away to show details thereof. cylinder, insuiiicient cooling is always the result. Th form of the device chosen for purposes of The reason for this is that the heat is removed illustration may include a base membe Ill havby the air blast from only a relatively small ing end pieces II and i2 mounted thereon in.

area of the cylinder as compared with the total which are rotatably mounted a plurality of rollarea of the cylinder that is heated by exposure ers 13, I'll, l5, l6 and Il for receiving a pluralto the light. Moreover, there is a tendency for ity of endless textile bands or belts l8. These the bands that pass around the cylinder to mainbelts are looped about the rollers to support for tain the cylinder at high temperature. The rotation a transparent cylinder l9 formed of bands become heated by exposure to the radiant glass or other transparent material. One or heat of the light source and by absorption of more of the rollers l3 to Il may be driven in heat from the cylinder. Inasmuch as the bands order to impart motion to the band and to roare poor heat conductors and poor radiators, tate the cylinder l9. they retain the absorbed and radiated heat and Within the cylinder l9 and .extending subtransfer it back to the cylinder. stantially axially thereof is a light source such An object of the present invention is to proas, for example, a mercury vapor lamp or tube which serves to illuminate the cylinder and the tracing and sensitized paper that are passed between the bands l8 and the cylinder 19.

In order to remove the heat generated by operation of the lamp 2!! from'the cylinder IS, in accordance with the present invention, I have mounted within the cylinder an elongated hollow member 2| which extends between and through the end pieces H and I2 and is supported thereate in cross-section so as to fit between the cylinder I9 and the lamp 20 while having a large surface area for absorption of heat.

Mounted in the base ll! of the device is a blower or fan 22 which is driven by'means of a motor 23 to supply air through a conduit 24 to one end of the heat exchanger 2|. The other end of the heat exchanger 2| is provided with a plurality of openings 2la through which the heated air is discharged from the heat exchanger 2|.

The construction described above has the advantage that air, containing dust, is not blown into the interior of the cylinder and, therefore. dust or other objectionable material cannot be deposited on the interior of the cylinder or the exterior of the lamp. However, a substantial cooling effect is obtained because the rotation of the cylinder l9 directs air over the heat exchanger which cools the air in the cylinder l9. If desired, the ends of the cylinder may be sealed by means of disk-lik pads II a and l2a, formed of felt or other material that is fixed-to the end members II and I2 and extend into the ends of the cylinder thereby preventing escape of ozone and excluding dust or dirt therefrom.

A further feature of the invention is that the heat exchanger is mounted in such position that it serves as a light shield for the portion of the cylinder not covered by the band and thus prevents the escape of light from the cylinder, serving to reflect such light On to the printing portions of the cylinder.

In order to cool the belts l8 of the device, air may be directed between the flights of the belts ill in contact with the cylinder l9 and the flights of the belts l8 engaging .the rollers I4, I! and I6 which are spaced from the cylinder. As shown in the drawing, the fan housing 22 may be provided with a duct 25 which extends beneath the lower flight of the belts l8 and then is turned upwardly and inwardly to form an outlet 25a that discharges air between the lowermost flights of the belts and the flights that support the cylinder l9. Such an arrangement makes for in creased cooling efflciency inasmuch as the air is constrained to flow through the space between the belts and, therefore, acts most effectively to remove heat therefrom. If desired, suitable deflecting baiiies may be mounted between the belts in order to divert some of the air upwardly behind the cylinder and thus into contact with a greater area of the belts.

From the foregoing description of a typical form of my invention, it will be understood that I have provided a simplified but highly efficient system for cooling printing devices of the cylinder type. It will be understood, of course, that the device is susceptible to considerable modification in the size and/or shape of the heat exchanger, and the cylinder, in the arrangement of the belts, and in the type of blower and the kind of light source used without departing from the invention.

Therefore, the form of the device disclosed herein should be regarded as illustrative only and not as limiting the scope of the following claims.

Iclaim: v l

1. In a photo-printing device having a rotatable transparent cylinder and a source of light within said cylinder; the combination therewith of means for substantially sealing the ends of said cylinder, a heat exchanging device interposed between said light source and a portion of said cylinder and projecting through said sealing means, said heat exchanger comprising an elongated hollow member sealed from the interior of said cylinder, means for supporting said heat exchanger in fixed position, and means for delivering a current of cooling fluid through said hollow member to withdraw heat from the interior of said cylinder. 1

2. In a photo-printing device having a rotatable transparent cylinder, a source of light within said cylinder and at least one belt passing partially around said cylinder and leaving exposed an area extending longitudinally of said cylinder; the combination therewith, of a narrow, elongated hollow heat exchanging member interposed bodily between said source of light and said exposed area of said cylinder and closely adjacent to the latter and sealed from the interior of said cylinder, and means for delivering a current of cooling fluid through said hollow member to withdraw heat from the interior of said cylinder.

3. In a photo-printing device having a rotatable transparent cylinder, a source of light within and substantially coaxial with said cylinder and at least one belt passing partially around said cylinder and leaving exposed an area extending longitudinally of said cylinder; the combination therewith, of means frictionally engaging and sealing the ends of said cylinder, an elongated hollow heat exchanging member fixedly interposed between said source of light and said exposed area of said cylinder, sealed from the interior of said cylinder and extending through said means for sealing the ends of said cylinder, a blower connected to one end of said hollow member for delivering cooling air into said hollow member, and means at the other end of said hollow member, forming openings for escape of air heated by passage through said hollow member.

4. In a photo-printing devic having a rotatable transparent cylinder, a source of lightwithin said cylinder, and at least one belt passing partially around said cylinder and leaving exposed an area extending longitudinally of said cylinder; the combination therewith of an elongated hollow heat exchanging member interposed between said source of light and the exposed area of said cylinder and sealed from the interior of said cylinder, members engaging the, ends of saidheat exchanging member and supporting the latter in fixed position, means on said members for substantially sealing the ends of said cylinder, and means for delivering a current of cooling fluid through said heat exchanging member to withdraw heat from the interior of said cylinder.

JOSEPH H. HRUBY. 

